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User story: Taking cultivations to the next level

Insights08 Jun 2016by Jane Carley

With the help of precision farming, one North Yorkshire farmer has managed to maintain profits in tough times and is now extending its use to cultivations with a GPS-guided subsoiler. Jane Carley reports.

A subsoiler fitted with an automatic depth adjustment system is helping improve efficiency.

Graham Potter has six years’ experience with precision farming since taking over the management of W Potter and Sons, adding variable rate-fertiliser, -slug pellet application and -seeding some three years ago.

Variable depth cultivation is the most recent development and Mr Potter is looking to target subsoiling costs by only working to the depth of the pans in pre-determined zones of each field.

With 200 hectares (494 acres) at Grange Farm, Baldersby St James near Thirsk, Mr Potter also takes on contract combining and ploughing to fund machinery investment.

Cropping is two wheats and oilseed rape, with spring barley now superseding third wheats, and one of the main challenges is tackling water logging.

Graham Potter has seen yield improvements from subsoiling, and hopes to cut costs with GPS-guided depth adjustment.

Trialling an Omni-Lift CL subsoiler from Yorkshire manufacturer Plowman Agriculture, working at uniform depth brought significant improvements to yields in 2015. And when the company announced a joint project with Soyl to develop an implement using its GPS AutoDepth active control system, he was keen to give it a go.

Mr Potter says; “We already use Soyl to scan the fields and generate soil type maps – there are 20 different soil types on this farm, and in-field variation is considerable. Yield maps revealed the improvements where subsoiling had taken place last season, but there is the potential for considerable savings from only working to the depth of the compaction layer.”

The Omni-Lift CL five-leg subsoiler is also equipped with Plowman’s Cam Lock leg system which allows individual legs to be lifted out of work in the field and safely locked into place, giving fuel savings of 15-50 per cent where only the two outer legs are needed to relieve compaction, says the manufacturer.

“We run a controlled traffic system, and we’re about to swap our 4.8m Claydon drill for a 6m version so we will only need to take out combine wheelings which can be done with just the two outer legs,” explains Mr Potter.

The centre leg can also be swapped for a mole drainer with its two adjacent legs taken out of work, increasing versatility further.

Working depth is adjusted according to values on a variable rate map, using sensors on the packer ram to measure its length and lift or lower the packer which puts the legs in deeper or lifts them out.

A soil probe is used to measure compaction depth at a number of sites in each field and these values are input into Mr Potter’s Gatekeeper farm management software.

“The depths tend to relate to the soil scan maps – compaction is often deeper down on light soils and closer to the surface in heavier patches,” says Mr Potter.

Additional data can also be added such as the positions of field drains or bed rock which could influence subsoiling depth at specific sites.

Values are generated or entered for compaction depth ratings for each part of the field using a grid which is then converted to a subsoiling map for importing to the tractor terminal as a job plan.

In Mr Potter’s John Deere 7R tractor cab, the variable rate map and guidance system on the tractor’s Greenstar terminal works with the Omni Till’s controller to dictate the working depth for each section of the grid. Using a sensor on top of the packer’s depth control ram, the subsoiler automatically adjusts its working depth accordingly.

“The adjustments themselves are small – no more than 80mm, but across the field this makes a significant difference to the amount of fuel used and the wear on the implement,” comments Mr Potter. “And across a number of fields, over several seasons, the savings should be significant. Compared to manually lifting or lowering the subsoiler the operation is much smoother, which should cut fuel costs in itself as the tractor is not working as hard.”

Application maps are generated from values entered into the farm office software, based on compaction measured and/or other field information. The map is then uploaded into the tractor's terminal, which, in conjunction with the subsoiler's control hardware, tells the subsoiler how deep to work based on its position in the field via GPS. The purple zones represent the least compacted areas in the field, while the dark red zones are the most heavily compacted and where the subsoiler will be working at its deepest.

The software is still very much in development, but can produce an ‘as applied’ map for the subsoiling operation which can be transferred wirelessly to the farm office, and in time Mr Potter hopes to compare fuel use, ha/hr and forward speed with subsoiling at a fixed depth.

“Accurate subsoiling will also pay dividends,” he suggests. “As commodity prices fall, the only way to increase margins is by increasing yields. Even with the drop in prices we did as well in 2015 as in 2011, which was a very good year.”

The five leg subsoiler legs, shins and points are faced with tungsten on their leading edges to reduce draft. Plowman’s James Kelsey says: “This also retains the design geometry as the faces wear and the consistency of working and thus compaction relief should be reflected in the yield maps.”

In addition to auto-reset legs, Mr Potter’s Omni-Lift is fitted with stone points using thicker sheets of tungsten with rounded edges to tackle the glacial stone on the farm. After 30 hectares (74 acres) of work they show minimal wear, says Mr Potter, who suggests they should be good for another 40 hectares (99 acres) or more.

Plowman’s James Kelsey reckons the system is simple enough to retro-fit to existing machines, and comments: “At the moment it adds £6,450 for the Soyl control box and £1,400 for the hydraulic system controllers to the £16,800 price of a mounted five leg Omni-Lift. We can see even greater potential with the larger trailed subsoilers that we manufacture.”